(1) Field of the Invention
The present invention relates to a toner cartridge and a control method of displaying the residual toner quantity in the same toner cartridge, and in particular, relates to a toner cartridge that is detachably set to an image forming apparatus that operates based on electrophotography or electrostatic recording technology or the like, and a control method of displaying the residual toner quantity in the same toner cartridge.
(2) Description of the Prior Art
Conventionally, as image forming apparatuses using electrophotography or electrostatic recording technology, copiers, printers, facsimile machines, multi-functional machines and the like have been known. In these image forming apparatuses, image forming is performed by forming an electrostatic latent image on the photoreceptor (toner image bearer) surface, supplying toner to the photoreceptor from a developing device to develop the electrostatic latent image, transferring the toner image that has been formed on photoreceptor by development to recording paper and fixing the toner image onto the recording paper with heat under pressure by means of a fixing device.
Since in image forming apparatuses of this kind, toner is gradually consumed, it is necessary to supply the toner.
For this purpose, in a prior art example, a toner supplying system in which a toner cartridge that contains toner is removably attached on the top of a developing device so as to supply the toner from the toner cartridge to the developing device, has been adopted, and in another prior art example, a toner supplying system in which an intermediate hopper is provided on the top of a developing device and a toner cartridge is removably attached on the top of the intermediate hopper so as to make the toner fall from the toner cartridge to the hopper and then supply the toner from the hopper to the developing device, has been adopted.
Further, when the residual toner quantity in the toner cartridge is detected to be low by detecting the amount of toner remaining in the toner cartridge or by estimating the consumption of toner by counting the number of pixels, replacement of the toner cartridge is recommended to thereby prevent interruption of operation due to toner supply.
On the other hand, for maintenance of toner cartridges and process cartridges, for prevention against attachment of incompatible units and also for recycling measures, recently the cartridges are equipped with a recording medium such as a barcode, magnetic card, nonvolatile memory, i.e., EEPROM, and the like, in which information for the aforementioned measures are written.
For example, there is a disclosed prior art technology (see patent document 1: Japanese Patent Application Laid-open 2001-22230) in which a contactless IC tag as a recording medium is provided for a toner cartridge so as to enable information on the number of recycled times, life, etc. of the toner cartridge to be written therein or written information to be read out therefrom, to thereby manage the usage conditions of the toner cartridge and its peripherals.
Further, in the color image forming apparatuses which have been increasingly used on the market, at least three, i.e., cyan, magenta and yellow colors of toners are used for development. Accordingly, the process speed for color image forming is low compared to the case of monochrome image forming, so is the number of printouts per minute.
To deal with this, as a prior art technology, for example the controller of the image forming apparatus is adapted to perform an initial adjustment process for its magnetic permeability sensor, immediately after power activation, at the warm-up time that is performed every predetermined number of printouts, at the time of loading the developer and when an environmental change of temperature, humidity and the like has occurred. In this initial adjustment process, the controller measures both the sensor adjustment value Vc for the magnetic permeability sensor at the lowest process speed and the sensor adjustment value Vc at the highest process speed, and determines the relation expression (linear expression) that represents the correlation between the process speed and sensor adjustment value Vc, based on these two sets of process speed and sensor adjustment value Vc. That is, an image forming apparatus with the controller that calculates the sensor adjustment values Vc at other process speeds based on the aforementioned relation expression is disclosed (patent document 2: Japanese Patent Application Laid-open 2004-53744).
Because the toner cartridge is equipped with a contactless IC tag, the configuration in patent document 1 is advantageous in terms of being able to manage the number of recycled times, life and others on the toner cartridge side. However, the contactless type configuration may be affected by noise from other electric parts, possibly causing malfunction. Also, from the viewpoint of cost performance, contact type recording media have been adopted under the existing circumstances.
Further, since, in patent document 2, the toner concentration of the developer is controlled based on the detection level of the detecting device (i.e., the magnetic permeability of the developer), it is possible to attain stable toner concentration control. However, there is no description as to the rotational rate of the drive motor, hence there may occur a case where toner supply cannot be correctly achieved. As a result, the residual toner quantity in the toner cartridge is misestimated, causing a fear that the toner cartridge is replaced by a new one even though the current toner cartridge has toner left therein.
Further, since it is demanded, in recent years, for the image forming apparatus to have a simple configuration and still achieve the full-color imaging function, the rotational drive force of a single motor is used to execute toner supply by means of gears, belts, etc., instead of using a dedicated toner supply motor for each developing device. This shared use of parts entails with the problem that proper toner supply in conformity with each of the developing devices cannot be carried out.